Role of stress evaluation on development of marine methane hydrate resources

摘要

Under the Japanese national research program for methane hydrate resource development, fieldrnsurvey operations including intensive data acquisition have been conducted in the Eastern NankairnTrough for a planned offshore production tests in the area. For a safe and stable operation, there arernseveral geomechanics-related issues such as construction of boreholes in weak sediments, stability ofrngeological formations, alternation of reservoir characters due to deformation and failure, and riskrnassessment for seafloor instability. To know stress states in the earth crust is an important subject ofrnsuch geomechanical studies. On the other hand, mechanical nature of unconsolidated shallowrnsubmarine sediments are different from typical reservoir rocks petroleum engineers usually work on,rnand applicability of methods and techniques employed for such deep rocks should be carefullyrnexamined. Some log- and core-based techniques have been tried to apply to the sediments for thernpurposes and reveal geomechanical natures of the region.